Electrical submersible pump assemblies (ESP) are commonly used to pump well fluid from oil wells. Conventionally, ESPs have been made up of a series of interconnectable modular sections including one or more pump sections with an associated fluid intake, a motor section and a seal or pressure equalizer section. Each of these sections includes an outer housing and a central rotatable drive shaft. The drive shaft has at least one splined end that will join a drive shaft of an adjacent module for rotation in unison.
A coupling sleeve with internal splines rotationally connects the two drive shafts. The coupling sleeve is a cylindrical member with internal splines located at each end. The housings of the modules are joined usually by bolting flanges together; alternately, an internally threaded rotatable collar may be employed to secure the housings.
An assembled ESP can be quite lengthy, up to and more than 100 feet. Normally, the separate modules are brought to a well site, then connected together. When two modules are joined to each other, a technician inserts a coupling sleeve over one of the shaft splined ends and axially aligns the two modules. The modules are brought toward each other, causing the splined end of the other module to stab into the coupling sleeve. The technician then secures the housings to each other.
The modules of an ESP are often interchangeable with modules of different capacities. For example, a particular pump module may be operable with a variety of different motor modules, and vice-versa. The shafts and their splined ends may differ from each other, requiring a variety of couplings. One coupling used in the past for mating different configured shaft splined ends employs a sleeve insert that is pressed into one part of the bore of the coupling. The sleeve has a splined configuration in its inner diameter that differs from the integrally formed spline configuration in the oilier part of the bore. Axially extending pins between outer diameter of the sleeve and the bore fix the sleeve to the coupling for rotation.